Generally capillary microcuvettes are used to perform an optical analysis on the liquid specimen which has been processed in a separate reaction with a proper reagent after it being collected, or to perform an optical analysis on the specimen directly after the collection.
For example, the conventional capillary microcuvettes have been used to optically detect hemoglobin in a blood sample. One example of such is disclosed in Japanese Patent (JP) No. 10-2941063, according to which, the prior art microcuvette is composed of a body member having two flat sheets, and a cavity formed in the inner surfaces of the body member. Also a detection zone is located at one portion of the cavity and is formed by the two inner surfaces separated at a certain distance. The cavity has an outer peripheral portion having a sample inlet and an inner peripheral portion having a channel that has a higher capillary force than the detection zone. Thus blood is introduced through the sample inlet and then blood moves to the detection zone for optical analysis.
However, the problem with the conventional microcuvette is that it can apply the blood specimen only through the sample inlet formed therein. This has resulted in the inconvenience that a finger of the subject needs to be aligned with the narrow sample inlet to apply blood to the microcuvette. The conventional microcuvette is particularly inconvenient because the capillary force to introduce the sample into the detection zone is only generated at a restricted area of the narrow sample inlet.
Further, the conventional microcuvette as described above becomes more difficult to use with blood samples collected beforehand and kept in a tube. For the blood samples in a tube, micropipettes are usually used for dispensing and applying the sample to the microcuvette. However the conventional microcuvette has a structure that is not very much compatible with the micropipettes.
In other words, to introduce or load blood into the conventional microcuvette, the subject needs to contact blood on his or her fingertip directly to the sample inlet of the microcuvette, which is only applicable when blood is provided right before the analysis from the body part such as fingers. However blood samples to be tested are usually collected and kept in a glass tube treated with anticoagulants (hereinafter referred to as a “collection tube”). Thus to take the sample from the collection tube and load it to the conventional microcuvette, extra procedures are required to bring the blood samples to be in contact with the sample inlet before the analysis. For example, one needs to tilt the tube to move its content near the mouth of the tube thus to bring the sample to be in contact with the microcuvette. Or one needs to pipette out some blood sample from the tube and transfer it to a slide glass before a blood sample is loaded onto the conventional microcuvette. However, the former extra procedure as described above may cause biohazardous problems if a blood sample is spilled out during the process. The latter, though it removes a risk of blood spills, may also cause a contamination problem during the process.
Therefore, there is a need to develop a microcuvette which provides a more convenient and safe sample loading system, where a direct loading from the fingertips is possible or the use of micropipette for loading a blood sample into the microcuvette is more conveniently performed.